Tracking issues with 1.0 and GNU/LLVM toolchain

[nashif]

The series zephyrproject-rtos/zephyr#94360 contains a set of SDK 1.0 compatibility patches. This is ready for review and merging.

• arch/x86 zefi build script fixes for picolibc as default C library.
• intel_adsp fails to build with GCC 14.3.
• adc_stm32 fails to build.
• cmsis-dsp module needs to use C library stdint.h for GCC 14.3.
• Add compiler_barrier in CODE_UNREACHABLE to avoid code deletion.
• ARM64 interrupt test failures. arch.interrupt and arch.shared_interrupt.
• ARM test failures. mps3/corstone300/an547 in arch.arm.pxn_without_userspace, arch.arm.pxn_with_userspace. GCC is inlining an explicitly labeled 'noinline' function.
• RX fails scheduler timeslice tests by a tiny amount. Increase the allowed error a bit.

SDK 1.0 builds -O2 and -Os versions of each library and startup file. This demonstrates the areas needing work, @tejlmand is working on a better solution, but this could be merged as a stop-gap measure.

• Need to pass optimization flags to linker. SDK 1.0 linker compatibility fixes zephyr#94359

Modules ready, only pending west update. These are ready for review and merging.

• TFM picolibc support. modules: Update trusted-firmware-m for picolibc zephyr#100544

Finished issues

• GCC 14.3 RISC-V -Os compilation bug. No longer occurs in testing with linked PRs. Could have been caused by code deletion in paths marked 'unreachable'?
• rpi_pico using newlib for boot_stage2.modules/hal_rpi_pico: Switch boot_stage2 to picolibc zephyr#94355
• cmsis_6 depending on newlib. modules/cmsis_6: Move to version with picolibc patch zephyr#94356
• silabs hal fails to build with GCC 14.3. west: Update silabs hal for both cmsis-6 and cmsis-5 compatibility zephyr#93895
• ARM test failure in libraries.cmsis_dsp.filtering.biquad.fpu. cmsis_dsp is doing an invalid right shift by a negative value. arm_biquad_cascade_df1_32x64_q31: asrl(val, -shift) -> lsll(val, shift) cmsis-dsp#7 west: Add cmsis-dsp fix for shifting by negative amounts zephyr#94362
• cmsis-dsp elicits some possibly undefined var warnings from GCC 14.3. west: Add cmsis-dsp fix for gcc 14.3 zephyr#94361
• PSA tests fail with GCC 14.3. modules/psa-arch-tests: Add GCC 14.3 support patch zephyr#94768
• mbedtls module fails to build with GCC 14.3. west: Add mbedtls fix for gcc 14.3 zephyr#94358

Current architecture pass status with the two PRs listed above

• arc
• arm
• arm64
• mips
• posix. Not relevant as this uses the host compiler.
• riscv
• sparc
• xtensa
• x86
• rx. Currently skips the C library tests.

[keith-packard]

arm64 interrupt test failures have been figured out -- it's gcc using SIMD registers as a part of va_start that is used in printk. Interrupts end up disabled after that, making nested interrupts fail. A patch for this is part of zephyrproject-rtos/zephyr#93042.

[keith-packard]

All of the pending Zephyr changes have been merged. At this point, all that is necessary for SDK 1.0 to 'just work' is either to merge #1039 or develop additional Zephyr PRs that would allow it to work with either SDK 0.17.4 or the current SDK 1.0 beta. I strongly prefer merging #1039 as that will be less disruptive to Zephyr work. If that is merged, a new SDK 1.0 beta should be released and any remaining issues cleaned up in preparation for a final SDK 1.0.